1. Field of the Invention
The present invention relates to a technique for protecting a screen surface from being damaged due to a fixed display operation of an image display apparatus such as a projection TV, and in particular to a screen protection method for a projection TV which is capable of protecting a screen surface from a continuous alarm message display operation in a state that a still picture is displayed for a long time or an external signal is not inputted.
2. Description of the Background Art
Recently, various kinds of large screen TV sets and projection TVs generally used for a presentation are introduced. The resolutions of the same are greatly enhanced, and the sizes of the same become large.
FIG. 1 is a view illustrating a conventional projection TV which includes an image source unit 1 for generating a bright image and outputting to a lens 2, a lens 2 for adjusting a focus of an image inputted from the image source unit 1 and outputting to a reflection mirror 3, and a reflection mirror 3 for reflecting the image from the lens 2 to a screen portion 4 and displaying the image on the screen portion 4. The operation of the above-described projection TV will be explained.
In the image source unit 1, the image processed by the system is produced and outputs a bright image using a bright light from an inner light source. The lens 2 adjusts a focus of the image inputted from the image source unit 1 and outputs to the reflection mirror 3. In addition, the reflection mirror 3 reflects the image to the screen unit 4 for thereby displaying the image on the screen unit 4.
In a usual time, since motion pictures are continuously displayed on the screen unit 4, a certain portion of the screen unit 4 is not easily damaged.
However, if a still picture is displayed on the screen unit 4 for a long time, or a corresponding signal is not inputted for a long time, a certain portion of the screen unit 4 may be rapidly damaged.
In this case, in the mode for receiving an external input, if the external input is blocked, as shown in FIG. 2, since there is not any external signal, a certain character message for requesting an external signal input may be outputted. In this case, a certain character message is continuously displayed at a certain portion of the screen, so that the portion in which the character message is displayed for a long time may be more rapidly damaged compared to the other portions of the screen.
In order to overcome the above-described problems, as shown in FIG. 2, an alarm character message is outputted for a certain time.
In the above-described conventional projection TV, in the case that an external input signal is blocked, and then in the case that there is no input signal, an alarm character message for requesting signal inputs is displayed. In this case, in order to protect a certain portion of the screen from being rapidly damaged, the output of the alarm character message is blocked after a certain time is elapsed.
Therefore, in the conventional art, a user can not easily recognize whether the projection TV is in a power on mode or a power off mode. In this case, a power consumption is increased. If the above-described situation is continued for a long time, a certain load is concentrated at a certain portion of the screen, so that the portion of the screen is rapidly damaged.
Accordingly, it is an object of the present invention to provide a screen protection method for a projection TV which is capable of effectively protecting a screen by movably displaying a message on the screen in a horizontal direction not by continuously displaying the message at a certain portion and randomly displaying a graphic or a character message on the screen.
To achieve the above objects, there is provided a screen protection method for a projection TV which includes the steps of displaying an alarm message at a certain portion of a screen, and changing a display position of the alarm message and displaying the alarm message when a fixed type alarm message display time elapses a set time.